Had gunman Edward Oxford got his wicked way there would be no Diamond Jubilee celebrations and street parties today.

The British Empire might never have happened, and England’s great royal dynasty could have been cut short.

Because the assassin’s victim was ... Queen Victoria.

The pistol-wielding Birmingham barman tried to shoot the Queen dead as she rode through a London park in June 1840, just three years after the young Victoria had taken the throne.

Oxford pounced as Victoria and her husband Albert, who she had married three months before, were carried along Constitution Hill in a horse-drawn open carriage. He fired two shots at the royal couple.

After a moment of stunned surprise, Oxford was quickly seized by an incensed crowd. He later stood trial at the Old Bailey, accused of high treason.

Having become the most notorious man in Britain, the 18-year-old Brummie was found not guilty by reason of insanity, and eventually committed to Broadmoor mental hospital.

Now, the Sunday Mercury has obtained records of his incarceration at the infamous asylum, shedding some light on the plot to kill a Queen.

Edward Oxford was born in Birmingham in April 1822. After completing his schooling he moved to Camberwell in London to take up work as a barman at The Hog In The Pound pub.

He quit his job in May 1840 and, just five weeks later, had formed his plot to shoot the Queen.

As Victoria, who was pregnant with her first child, and Prince Albert left Buckingham Palace in the carriage on the sunny evening of June 10, the would-be assassin had already taken up position on a footpath near Constitution Hill.

When the carriage drew level, Oxford emerged with a pistol in each hand and fired two rounds at the royals.

He was wrestled to the ground by onlookers, and calmly declared: “It was I. It was me that did it”.

Investigators quickly raided his lodgings, finding intricate rules he had drawn up for an underground military alliance called Young England, whose members were to be armed with pistols, rifles and daggers.

While the terror caused by Oxford was very real, and resulted in a wave of public support for Victoria, the authorities never managed to find any bullets at the scene, and his defence team maintained the pistols he fired were only loaded with gunpowder.

His trial began at the Old Bailey just a month after the assassination attempt, with a crowd of spectators present and a media storm to rival any modern day court case. It was tipped as the trial of the century.

The teenage gunman sat oblivious in the dock as his defence team pleaded his insanity, citing both the alcoholic tendencies of his grandfather and the abusive nature of his father.

His mother Hannah took the stand, detailing the violent home life ‘her Edward’ had suffered and telling the jury how her son had been prone to fits of hysterical laughter, following which he often cried for no reason.

Then the finest minds in Victorian medicine were called as witnesses, and all told the same tale, that Oxford was of unsound mind.

The jury quickly made up their minds, and he was acquitted of high treason, but sentenced to an indefinite term in a lunatic asylum.

The reviled Brummie began his time behind bars at Bethlem, where records from 1854 reveal he “conducted himself with great propriety at all times”.

He took to studying French, German, Latin, Greek and Spanish, while lending his painting and decorating skills to help around the hospital.

When asked about his crime, doctor’s notes say that he was repentant.

“He now laments the act which probably originated in a feeling of excess vanity and a desire to become notorious if he could not be celebrated,” his medical notes read.

Oxford was moved to Broadmoor in 1864. He was by now 42, having spent more than half his life in an asylum. On his initial assessment by medics at Broadmoor he was described as “a well-conducted industrious man, apparently sane.”

He told doctors that he had fired the pistol to gain celebrity status, and “had not the smallest intention of injuring Her Majesty”.

With experts now convinced of his sanity, they began petitioning for his release.

After three years of trying, in 1867, Home Secretary Gathorne Hardy agreed to free Oxford, on condition that he move to one of the colonies and never set foot in Britain again.

The Government organised a passage to Australia for the would-be assassin, 27 years after he fired those fateful shots at Queen Victoria.

Before he left, a dozen officers from the Metropolitan Police spent a day photographing, fingerprinting and taking notes on Oxford, just in case he should try to return. He travelled to Plymouth on November 26, 1867 and boarded the HMS Suffolk next morning, bound for Melbourne.

But the story of Edward Oxford continued to take bizarre twists and turns even after he arrived down under.

In 1880 he was arrested for stealing a shirt, and spent a week in jail. Reports also suggest that he was up before the local magistrates for vagrancy, and that police were told to keep an eye on his “eccentric conduct”.

He later changed his name to John Freeman in an attempt to escape the notoriety he had once craved. In 1888, at the then ripe old age of 66, he is said to have published a book titled Lights and Shadows of Melbourne Life.

After a career as a house painter, and having married while in Australia, it is understood that Oxford died at the age of 78, in 1900.

It was the end of a remarkable story that Birmingham would rather have forgotten.

But Edward Oxford remains, despite all attempts to airbrush him from history, one of the most extraordinary Brummies ever.